The invention relates to a suction filter to be attached to a tip portion of an inlet pipe for sucking fuel in a fuel tank and feeding the fuel to an engine or the like of an automobile to filter the fuel.
As shown in FIG. 5, a pump b for feeding fuel in a fuel tank a to an engine is disposed in the fuel tank of an automobile, and the fuel is sucked through an inlet pipe b1 provided to the pump b and sent to the engine through a fuel filter c.
In this case, as shown in FIG. 5, a suction filter d is also attached to a tip portion of the inlet pipe b1 to remove relatively large impurities. The suction filter d is positioned to abut against a bottom surface of the fuel tank a.
Heretofore, a suction filter having a structure as shown in FIG. 4 has been known. More specifically, a brim-shape flange d2 is integrally formed at a lower end portion of a pipe portion d1 to be connected to the inlet pipe b1 of the pump b; the pipe portion d1 is inserted into a pipe attaching hole d4 provided to an upper filtering fabric d3; and a pressing clip d5 is attached to the pipe portion d1 so that peripheral portion of the pipe attaching hole d4 of the upper filtering fabric d3 is sandwiched between the upper flange d2 and the pressing clip d5 to attach the upper filtering fabric d3 to the tip portion of the pipe portion d1. Then, a conical shape coil spring d7 is attached to a spring attaching portion d6 projecting downward from a lower surface of the flange d2, and a lower filtering fabric d8 is provided to cover the coil spring d7. Thereafter, the peripheral portions of the lower filtering fabric d8 and the upper filtering fabric d3 are thermally bonded together to form a filtering fabric bag d9 at the tip portion of the pipe portion d1.
As shown in FIG. 5, the suction filter is attached to the tip portion of the inlet pipe b1 of the pump b located in the fuel tank a and the filtering fabric bag d9 is positioned to abut against the bottom surface of the fuel tank a. At this time, the filtering fabric bag d9 of the suction filter always has a specific size by the coil spring d7 provided therein, so that the filtering fabric bag d9 is not crushed to become flat, and also, the lower surface of the filtering fabric bag d9 always abuts against the bottom surface of the fuel tank a by the elasticity of the coil spring d7.
However, the conventional suction filter as shown in FIG. 4 has the following defects:
1. Since the upper filtering fabric d3 is sandwiched between the flange d2 and the clip d5 to fix the filtering fabric bag d9 to the pipe portion d1, the filtering fabric bag d9 is liable to be disconnected;
2. Since the lower surface of the filtering fabric bag d9 is directly pressed against the bottom of the fuel tank due to the resilient force of the coil spring d7, there is a risk that the lower surface of the filtering fabric bag d9 wears out; and
3. When the upper filtering fabric d3 and the lower filtering fabric d8 are thermally bonded together to form the filtering fabric bag d9, it is hard to accurately and firmly laminate the peripheral portions thereof and set them onto a thermal bonding machine due to the resilient force of the coil spring d7. Thus, creases and lines may be formed on the filtering fabric bag d9 and the peripheral portions of both filtering fabrics d3, d8 may not be thermally bonded together firmly.
In view of the above problems, the present invention has been made and an object of the invention is to provide a suction filter, wherein the above mentioned three problems can be solved, so that a highly reliable suction filter can be produced with good productivity.
Further objects and advantages of the invention will be apparent from the following description of the invention.